This ongoing project consists of several components: One component considers a fixed and a random effects model for combining data from a series of comparative trials. The study evaluates the performance of each method under various heterogeneity assumptions and with several scales of measurement, including the risk difference and the odds ratio as measures of effect. Another component develops and compares parametric and non- parametric tests to assess the assumption of homogeneity of effects in data from a series of trials. This component considers data from Gaussian, binomial, and poisson sampling distributions. A third component extends and adapts the meta-analytic methods appropriate for clinical trials to combining the evidence from a series of epidemiological studies (both case-control and cohort designs). Partial results from this component appear in the Journal of Clinical Epidemiology. A general application of the methods of this project appears in Clinics of Applied Nutrition. This work is still in progress.